Her father James Mathieson said: “I believe that both Melissa and Jason Conroy were badly let down. They were both failed by the services that were supposed to protect them.”

Image copyrightAvon and Somerset PoliceImage caption Jason Conroy showed “abnormal sexual drive” from a young age

Key findings of the Serious Case review included:

A forensic report, overlooked by the care home, detailed Conroy’s previous history, saying staff should be “made aware of his victim profile – young petite women who he can easily overpower” and that he “goes to some lengths to identify potential victims including taking an interest in staff rotas”.

Conroy had tried to kill his mother on two occasions, and she had tried to warn staff about his behaviour. After one attack she told staff that “he wanted to kill her and have sex with her”.

In 2007, while at a residential school, Conroy became fixated on a young female member of staff and tried to strangle her with a dressing gown belt. “It is stated that he had reportedly said that he wanted to kill her and have sex with her dead body,” the report said.

In March 2013, he sexually assaulted then tried to strangle a care home worker. In a subsequent investigation, Conroy “explained that he had wanted to have sex with her but knew this was against the rules. He had therefore tried to kill her because she would no longer be a member of staff and so he could have sex with her without breaking the rules.”

Concern of his placement were also raised by the Adult Disability Panel at Conroy’s home authority as no consultant care was provided.

Conroy was moved to Alexandra House as his behaviour was too challenging for the care home to deal with.

‘Not streetwise’

However the Serious Case Review found the initial assessment made by the care home was too positive and didn’t take seriously the warnings of the forensic assessment.

Appropriate levels of supervision were not put in place which ultimately led to him being allowed to murder Melissa, the report found.

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Miss Mathieson’s family, from Windsor, did not want her placed in Bristol, describing her as “vulnerable” and not “streetwise”.

Mr Mathieson said: “Even though the Safeguarding Adult Board’s investigation rightly found that Melissa’s death could have been predicted and prevented, as a family, we are still left with so many questions about how this could have ever happened.”